1. Field
One embodiment of the invention relates to a sound corrector that reduces the resonance peak of a signal, a sound measurement device, a sound reproducer, a sound correction method, and a sound measurement method.
2. Description of the Related Art
Portable sound reproducers have been commonly used to listen to music playback or the like through a headphone or an earphone. When a user listens to music or the like with a headphone or an earphone, the headphone or the earphone blocks the ear canal, and thereby a resonance phenomenon occurs. The resonance phenomenon causes unnatural sound quality. Accordingly, to prevent the resonance phenomenon, there have been proposed various technologies.
For example, Japanese Patent Application Publication (KOKAI) No. 2000-92589 discloses a conventional technology using a microphone integrated earphone. With this conventional technology, the acoustical properties of the ear canal are measured by using the microphone integrated earphone. Then, the acoustical properties are corrected with an adaptive equalization filter.
For another example, Japanese Patent Application Publication (KOKAI) No. 2002-209300 discloses a conventional technology using a dummy head. With this conventional technology, the acoustical properties of the ear canal are measured at the position of the eardrum by using the dummy head. Then, a correction filter is created based on the acoustical properties to correct the acoustical properties with the correction filter.
For still another example, Japanese Patent Application Publication (KOKAI) No. H09-187093 discloses a conventional technology in which a filter is created to reduce measured resonance peaks.
In the case of the conventional technology using a microphone integrated earphone, the properties of the microphone is included in the acoustical properties to be adaptively equalized. Besides, the acoustical properties cannot be appropriately corrected depending on the position of the microphone.
In the case of the conventional technology using a dummy head, the ear canal varies among different individuals, and also there is a difference in properties between the left and right ear canals of a person. Therefore, with the correction filter created based on the acoustical properties measured using the dummy head, the desired effect cannot be achieved.
Further, Japanese Patent Application Publication (KOKAI) No. H09-187093 discloses the technology in which a filter is created to reduce measured resonance peaks, but it does not specifically describe how to create the filter. Generally, a reverse filter of measured data or a parametric equalizer is used. However, since the measurement cannot be performed at the position of the eardrum, an accurate correction cannot be achieved. In addition, there are numerous parameters in a parametric approach, and therefore, tuning is difficult and the desired properties cannot be obtained.